In a smooth top cooker, a smooth top, normally of glass ceramic, overlies one or more heaters comprising a metal dish, for example of circular shape, in which is provided a base layer of thermal and electrical insulating material. One or more electrical heating elements is or are supported in the dish, such element or elements comprising coiled wire and/or electrically conducting strip and/or one or more infra-red radiating lamps, for example of tungsten-halogen form. A peripheral wall of a thermally insulating material, such as a ceramic fiber material or vermiculite, is normally provided around the heater and, when the heater is installed, the peripheral wall contacts the underside of the glass ceramic smooth top with the heating element or elements being spaced from the smooth top.